The vet will have done a thorough job, and from what you've said he seems to know his stuff. Milbemax is one of the leading brands of wormers - the favourite seems to be drontal.
Ear mites...
I'm sure you vet will have examined him for these, and given you the necessary ear drops. But signs of ear mites are excessive wax build up and scratching. Tip -very gently rub against the side of the cats ear - behind the bit where the ear lobe would be one you. If the cats starts frantically scratching, it's a good indication the cat has mites. (The rubbing makes the mites run around, which brings on the scratch impluse.)
J20, it depends where you got this cat from, but most rescues will have already treated him for fleas, worms and mites.