foremilk imbalance or dairy intolerance?

I'm starting to second guess myself, but I have been going back and forth on if my 5 week old (EBF) has a dairy intolerance or if I just have an oversupply. first I do already have a stash of over 100 oz of milk since I started pumping during his first week due to latch issues, which are now resolved. if I bottlefeed his poo is mustardy/seedy, but he will on and off have more green poo when at the breast. i try to do blockfeeding but my other breast gets super uncomfortable so I'll usually put him on the other breast after 15-20 minutes. when I pump it usually will take 30 minutes to completely empty. he is again 5 weeks and is gassy, and most of the time whines or cries before pooping. hes getting a "rash" on his face that does resemble baby acne. basically, I want to make sure I'm not ignoring a dairy intolerance and making him miserable but I really rather not go down the elimination route unless absolutely necessary.