Randomly having extreme side effects when I normally have none

So I am on the highest dose (15 mg) and typically tolerate my dosage just fine with literally zero side effects. Before I started using compound tirz, I was on Zepbound (before insurance stopped covering it) and even with the name brand I would occasionally have a one off shot that gave me mild side effects like sulfur burps and a little bit of gastro distress. But otherwise I'd have no side effects. I've been on this med for about a year now.

I took my most recent dose on Saturday evening like I usually do. By Sunday afternoon I was SO sick, having constant diarrhea every 15 minutes to the point where it was just straight water going through me. The sulfur burps were unbearable. I was so bloated and uncomfortable. Monday I still had the same issues just a bit milder, trying to recover by drinking electrolytes and bone broth. By today (Wednesday) I feel mostly fine, but I'm still so confused on why I had such an extreme reaction when I don't usually experience side effects.

It's worth noting that this most recent injection I started a new vial. I get my medication through GimmeCare with no additives, and have had zero issues with my injections from my previous vials with them. This one came in the same shipment as my previous 2 vials.

Has anyone else had this experience of tolerating it just fine and then just randomly having crazy side effects at the same dosage? Should I worry about whether my vial was dosed incorrectly? I'm thinking about lowering my next injection dosage by half, but I'm still concerned about whether there's an issue with that specific vial.