What does "8 or 10 pieces
of hay' even means? A rabbit should eat his body in hay everyday. If he doesn't, try another hay. Or grass. Give less pellets (you shouldn't give garbage like walmart pellets anyway - your logic about the walmart thing is like saying everything in supermarkets is good for your health because someone put those things in there).
Use your common sense: what do you think rabbits are eating in the wild? Pellets? Of course people who produce and sell pellets are going to tell you it's what best for your bunnies - you have sellers who know and care nothing about rabbits in front of you, they only learnt a short selling speech during their first week so that they could sell as much things as possible to gullible and uninformed people. NEVER take advice or buy an animal in a petshop, you'll only end up with a sick or dead pet.
From what you're saying, it's urgent you change your rabbit's diet quickly or he won't see his next birthday. As several people recommended, you have to go read all the house rabbit society website (who is written by people who know rabbits, manage rabbits' rescues and successfully keep them alive for decent amounts of time), especially the diet article:
It's your choice, but you came to ask the opinion of people who have had rabbits for a long time (I've had my current bunnies for respectively seven and half a year and three years they never had any problem linked to their diet). If you choose not to change anything and that your rabbit comes down with stasis again and ends up dead, which seems like a probable outcome from what I've just read, don't say you weren't warned. Doing the right thing by your rabbit is really not hard, you just have to read a few articles and change a few habits. If you've got more questions, you can ask them here afterwards.