Mystery Baby Problem...Help, Please!

I am desperate for help with this issue, so I appreciate any moms or dads who can read through this quickly and let me know if they've experienced anything similar with any of their children and can guide me with what to do. BabyG has been a spitter-upper from day one, but was not anywhere as bad as her reflux-ed older brother. She's also been notorious for not having the greatest latch during nursing and often sputters/sucks in air while nursing (I'm hoping to talk to my aunt, who's a lactation consultant, at my awesome cousin Amy's bridal shower next Saturday). However, last Thursday or Friday(so when she turned five weeks old, basically) there was a sudden change in BabyG and I just can't figure out why. Symptoms that all began simultaneously and continue now include the following: 1. She went from pooping regularly (several times a day) to going a day or two in between. 2. She started being extremely gassy. I don't recall her having gas at all before but now she has it all the time, sometimes almost explosively. 3. Her spitting up increased (I would venture to say it doubled or even tripled) in both frequency and quantity. It also can be very explosive and projectile in nature. She now rivals LG in his spitting-up glory days. 4. From number 2 and 3, she seems extremely uncomfortable a lot of the time. Sometimes during nursing, sometimes afterward, sometimes in between feedings. 5. I don't think this one started at the same time as numbers 1-3 but is likely a result of them - she hesitates to nurse and sometimes won't start for a full minute or more. She obviously will WANT to nurse but will resist latching on. This doesn't seem like reflux to me - I don't see a ton of tongue-thrusting or back-arching (though she has done a bit of each in the past). I've been able to put my finger on dairy, chocolate, and raw tomato bothering her, so I already avoid those. I thought initially that all of this behavior change was due to my having hummus a couple of times (and her reacting badly to trying to digest beans), but I haven't had hummus since Monday. I think it's chiefly a gassiness issue - she sucks in air all the time. When she spits up, she gags and sucks LOTS of air in. I think that covers everything. I'd really like to get this solved so she's not miserable so much of the time. I guess it could all come down to that poor latch that I hope to fix, but it's just weird to me that this all came on at once. I will likely take her to the pediatrician next week if I can't figure anything out. Thanks for any help or wisdom you can provide in advance!