TPLO Surgery / Infection / Recovery?

My poor lab / rottie cross has had a bad time of it. He is 5 in Jan. He had TPLO last year on his left leg - all went well - however he developed an infection exactly 3 weeks afterwards and was promptly put on a drip and had numerous antibiotics - 3 different types.

He had TPLO on his right leg 3 weeks ago - it was all going well. We once again did all the right things, took it in turns to sleep in the lounge with him, restrict his movements, keep him entertained, washed his bedding daily - he has another infection - again, exactly 3 weeks after surgery !!!

My boy (Oscar) was the runt of the litter, but i saw him as the most gorgeous baby I have ever seen. We got him from Battersea and was told that his mother had kennel cough and to watch Oscar closely as he was very small (1.95 kilo) and you could see his ribs. After a week he had his injection and developed kennel cough (it can be in their system for up to 10 days before developing)- after going to the vets about 15 x about it as it seemed to be quiet severe to me, it turned out he had bronchial pneumonia and worms in his tummy - He was kept in the surgery for 3 weeks in an incubator and the vet told us that if i hadn't been insistent then he would have likely not survived that weekend (i took him in late Friday night). I am not knocking Battersea - they do a fantastic job, by the way.

Anyway, the reason i give you this history is so you can see that Oscar has been through it in his short life and as such the vet seems to think that he gets the infections after TPLO because he has a weak immune system.

My question is. Oscar is on about 10 antibiotics a day (3 different ones) as well as Metacam - given at 48mg as per his weight - he is 48 kilo's now - he likes his food :-).

He was sick last night, i called the vets (emergency vet at 2 am) and he said to go through his sick and if there are no tablets in his sick, don't worry about it......I did that but today my happy bubbly boy is quiet depressed, his leg is hot, he doesn't want to play, just cuddle and when he moves around he moans. The vet seems to think I should wait another day or so before bringing him in, however after previous experiences I trust my instinct more - do you think i should insist he goes into the vet surgery and goes on a drip (like he did before).

I would just like somebodies opinion please - i am a nightmare mum as you can see - all the receptionists at the surgery know me instantly now and call Oscar's name without checking the diary - as i seem to be living there and have been for years now (i have another dog - who has a very strange skin complaint - she is from Battersea too).

I forgot, Oscar keeps staring at me too - he always does that with me because he knows that I respond to it - we have an amazing connection- so he is obviously trying to tell me something

should i just be patient - i would just like a second opinion or hear from anybody that has been through something similar?

Thank you