Different brand mesalamine not working?

I’m 22, have Crohn’s and I have been taking Mesalamine extended release capsules since 2012. I was on name-brand Apriso until 2020 when Lupin (manufacturer of Apriso) began making a generic version of the same medication. Both have worked fine for me. I have symptoms but they’re manageable with Apriso.

2 weeks ago I picked up my prescription and it looks different than normal so I check and it’s manufactured by a different company, Zydus. It’s also extended-release capsules and the same dosage of the same drug so it should be fine. But since then I have experienced worsening gastrointestinal distress as well as symptoms I don’t normally experience - throat bleeding, bloody stool, far worse esophageal pain especially while swallowing pills, & overall inflammation (arthritis, headaches etc). The stuff that my medication usually works to keep at bay.

In the last month I also started taking lamotrigine for bipolar disorder but there are no interactions between lamotrigine and mesalamine, and these symptoms began with the new mesalamine Rx. I contacted my doctor about it (no GI right now unfortunately) so hopefully I can get it sorted out. And hopefully it’s not an insurance problem because out of pocket Apriso can be up to $600.

My question is - has anyone else experienced a different effectiveness with the same drug/dosage manufactured by a different brand? I can’t find any information online about the difference between Lupin mesalamine ER and Zydus mesalamine ER so I’m kind of stumped & scared as to how my body could be having this reaction.