J.☯.
When you say "exclusively breast fed," do you mean he's never had a bottle or just that he's never had anything in the bottle besides breast milk?
If he's never had a bottle (of anything) before, this could be part of the challenge. A part of him is probably thinking, "What the heck is this, and why should I put it in my mouth?" Since he is 6 months old, you could skip the bottle altogether and try giving him a sippy cup. My kids looked at a sippy cup and didn't know what to do with that, either. So I used either a Playtex or Gerber and took the valve out (so that it dripped). Didn't take them long to get the idea of what a sippy cup was for. Do you have any expressed milk? If you do, you could put that in the sippy cup so that he's familiar with it.
If he's had a bottle of breast milk before and it's the formula that's the problem, you can try a couple mixing the formula with breast milk until he gets used to it.
It sounds like he's mad that you're not just nursing him. But if you think he's getting sick because the formula is upsetting him, I think Nicole is right and you need to call your ped. He might have an allergy that you don't want to ignore.
Finally, solid foods. At 6 months, he's probably still very new to solid foods and might just be adjusting. You could always try something that he can pick up with is fingers - small pieces of a whole wheat bagel, graham cracker, Gerber biter biscuit or snack. It doesn't necessarily have to be something nutritious right now, just something safe that will help him learn what to do with it. My kids both rejected being spoon fed, so I had to get creative with finger foods.
Try to relax. He really will figure it out. Good luck!