>> I have my Son to help, but to be honest he's not a great assistant and can't really hold him still enough.
Don't hold pup still with force, it will make him frightened & even defensive as well as breaking his trust in you and therfore making the situation worse the next time you need to check/clean/treat his ear.
The trick is positive association. Ideally this should be started as soon as you get pup, so they become accostomed to having thier ears/teeth/eyes/paws/body checked, but it is something lots of people don't think about doing.
With Buster I would sit him down calmly, then gently touch his outer ear & say 'looking' (this is my 'command' for any examinations, LOL) & give a treat straight away. I would then make the touch last longer, if he was getting bored/not enjoying it I would also say 'wait' (he knows a treat follows 'wait' if he waits nicely :) ). I gradually built up from there, so now I can look in his ears, put cleaner in them etc., all with the commands 'looking', because he knows I am not going to hurt him, or force him and he will get a treat (a few treats inbetween if I am spanding a while checking his ears out).
If pup is really keen to please for specific things, eg. at meal times (Buster will do ANYTHING to get his bowl put down!!), you can use that to your advantage while working on the positive association.
If your pup didn't just have to go through the ordeal with his ears at the vets, then it would be an idea to get him to lay down and try when he was relaxed and ready for sleep, but as the vet has just physically forced him to have his ears checked, you pup may feel threatened laying down. It could be worth starting with pup standing, so he has the option of walking away if he is frightened. If he does walk away, don't force him back, encourage him and if that doesn't work, leave him a little while and try again later.
The more often you practice working on the positive association & the better you timing for praise & rewrd is (you also need to be calm & nice, not forcefull), the quicker pup will learn. You can do this several times a day, but keep sessions short and alsways aim to finish while pup is happy, son't push it untill he is getting fed up/frightened.
All in all, there is no magic quick fix.