Poorly cat discharged from vets for weekend but still not right.

[Milliways]

Millicat is 13 and always been in prime health and an avid hunter.
A few months back he went off his favourite food and I started the game of what will he eat, but luckily he took to dried food more (IAMS and Purina replaced his Whiskas) and he would have half a Sheba tray morning and night in place of his old Felix.
He had his annual MOT at Christmas, I mentioned the food and they found the start of tooth decay. He was vaccinated and wormed and booked in for dental work, which he had about a month ago.
Last week we were away and neighbour feeding him. We had to come home early as he stopped eating and drinking anything, even the cat milk we use as a treat. When I got home he was terribly weak, couldn't stand. Took him to vets who admitted him on a drip as he was very ill.
Turns out he then had awful bloody diarrhoea and then passed spectacular tape worms! I worm him! They let him home on Saturday afternoon as had started to eat that lunchtime, but he is still hardly eating anything so giving him his antibiotics is not happening well. He takes a mouthful or 2 then goes back to sleep.
He is back on Tuesday for more blood tests. He was anaemic but that improved, but there is a worry over his Pancreas function.
I feel it is my fault about the worms, but the vet gave him the last tablet in surgery at Christmas, so was due end March whilst we were away. He missed one last year but they said that shouldn't really matter as he does get wormed mainly on time.
Anyone else had this? How long did it take to recover?

Mcat once had a bad case of worms, when it was just him and (my now) Dh. who'd forget to worm him Also an avid hunter. The hunters are more prone to worms.

He was a very young cat then, so didn't get weak or anything. Just got skinny, dull coat.

Can your vet advise you on whether it's OK to worm him more often than the usual 3 months? Maybe a different wormer to the one he's getting? I know fleas can become immune to flea meds. Maybe worms can too?

What wormer do you use ? (And what wormer did the vet use at Xmas?

Not had this but our cat has had a few bouts of pancreatitis and 'hospital' admissions.
He can't have normal food and has to have special biscuits and wet food which we buy online. Let me know if you want the names of them if this is something you might need to pursue.
Hope Millicat gets better soon

Thanks everyone. We use Milbemax wormer as well as regular flea spot on stuff. As I said, he did miss 1 last year so maybe it grew too much for the next emmer to shift? He was wormed again in the vets this week of course and I will speak to them about maybe switching brands.

Milbemax is an excellent wormer, but advice is that avid hunters should be treated for tapeworms every month as they have a much higher exposure due to eating vermin etc.