I have an appointment at the vets in the morning but just wanted to ask here too

I have a 18 week old GSD, she has been itching and biting for a few weeks, been treated with frontline and drontal monthly and no fleas seen

Took her to vets a few weeks back who emptied her anal glands which made no difference at all

She is fed on Royal canin maxi junior, her coat is lovely and her stools fine

My vet did mention giving her steroids which I'm not too sure about, just looking for any advice before I go in the morning

I would be wary of giving steroids to such a young dog with an undiagnosed problem, I do know a few GSD's who have been allergic to Frontline so maybe if you can't see any fleas perhaps don't treat her again for several months, vets do tend to say "flea allergy" to a dog presenting with scratching. It may be as simple as her being hot in the nicer weather or starting to change to her adult coat, I would probably look at an anti-itch over the counter shampoo and wait a bit

Of course she could easily be reacting to the chemicals your dosing her with.

I stopped using flea sprays routinely when one of mine had quite a bad reaction to Frontline spot on that I had to use for Pet passport travel in those days, she ended up chewing chunks out, looked moth eaten for months until the next moult (as the new coat regrew a different shade),

It may well be the food if not a reaction to the flea treatments or possibly vaccines. I wouldn't give any more it certainly wont be helping imo  Mine havnt had any chemicals for fleas and worms since pup as I only  treat if something is there to treat. How about a bath in a gentle dog shampoo. or even oatmeal soaked in water and use the water. also rinsing in applecider vinegar can help. If all that fails I would look at changing food. I feed raw so that would be my go to but if that's not suitable for you then a grain free kibble with as few ingredients as possible. something like millies or eden available on line. Rc although many vets ar every keen is not the best food imo. If you can avoid having steroids  it would be better but of course you have to balance how bad she is while you look for the cause.
If all else fails a dermatologist referral could be very useful
If you ask the vet for a shampoo he will probably give you malesab which I find suits mine but it can be drying and doesn't suit every dog

Thanks everyone

She wasn't like it when we collected her, after a vet visit vaccination, frontline and drontal within 2 weeks it started

We obviously stop her when we can but today I went to work for 3hrs she was in her crate which she loves I could tell she had been biting and checked her and she has a few sores

Really don't want to use steroids but it's not fair on her, she bites her front paws/legs, tail, and back end of her body

Problem with steroids is that they will probably stop the itch but they don't cure the cause, you cannot keep pup on them long term and as soon as you stop the underlying problem will re-appear.

Yes, that's my worry
What about skin scraps ? I want to be fully informed when I go tomorrow

Has she any dandruff? There is a mite called the Cheytiella (sp?) also nicknamed walking dandruff that is quite common in pups and makes them extremely itchy. Frontline spray is the most effective. The vaccine,wormers,stress of home change  etc can knock there Immune system leaving them vulnerable.

No, no dandruff her coat and skin look fine apart from where she has a few sores from biting

It does sound like an allergy of some sort even if it's to  flea or vaccines. At least u can stop them now. I would start with looking at diet and if you have to give a short course of steroids don't panic.although not ideal it may stop it getting worse while.u explore options. If tje vet doesn't want to explore other options do go for a referral.I have two with allergies and we only started to get somewhere when we got to the specialist and I have a good general vet but it need a specialist  to guide us.skin scrape may find out if there is any parasites  . I have used steroids in my gsd at times as things got very bad but now we know where we are going we rarely need any and then only a tiny amount