I haven't experienced the same thing, but I know that what you're going through must be really frustrating! I hope it passes quickly so you and baby can get back to your normal feeding routine.

My first thought was that your little one might be sick, or that your milk might have a different taste lately. Or it's just a nursing strike.

If you're really worried, make an appt. with your doctor - even if its just to ease your stress!

Some good info here, and some great links at the bottom of the page:

http://kellymom.com/bf/concerns/child/back-to-breast/

It might be thrush. Does your LO have white spots in his mouth? Not on the tongue but on the gums and the sides of the cheeks (on the inside)? This can make it painful for him to feed. One other reason I heard for nursing strikes is forceful letdown, where too much milk at once overwhelms the baby.. had you noticed him choking on your milk prior to the strike? I'm sure there are other possible reasons, these are just two that I learned about when researching various things.
A visit to a lactation consultant might be really helpful and you should also discuss it with his ped as you mentioned it might be affecting his weight gain.
HUGS and I hope things get better.

Could it be colic? Perhaps try infacol and gripe water. My daughter had bad colic about this age.

I think lots of good advice already. For my guy, we used the nipple shield from about 5 days old, so even though I had a horribly fast and hard letdown, it slowed it enough for him. Now that he's almost 5 months and not using the shield, he's big enough to handle my fast letdown anyways.

The cottage cheese spit up sounds normal; its just been down a bit longer. As long as it doesn't develop into projectile vomit and of course as long as baby is gaining well, I wouldn't worry about that except as a laundry issue.

I've heard quite often that drinking or taking fenugreek can cause a taste change and/or belly pain for the nurslings.

Could be a nursing strike due to the letdown; try either hand expressing just a bit, or pumping just past the letdown. This will relieve some of the pressure so baby doesn't have as much to 'choke' on. Try not to use any bottles, just because you've already noticed that affected your supply. Baby could be frustrated at the breast if he is used the ease of the bottle and maybe the letdown isn't happening as soon as he would like. I might also suggest nursing in different positions, like side lying in bed, because then if there's too much milk, he can just let it dribble out while he's nursing. Or maybe that hurts his belly, so try a more upright position. Another thing you can try to help any belly pain would be burping really well, especially when changing sides.

You know your baby and I hope you find what works! Sending love!

If you feel like its a supply issue, you could offer supplement through an at-the-breast supplemented, like a Medela SNS or a lacy-aid. You might also want to consider briefly reducing the dairy in your diet, in case LO has an intolerance.