I agree with Deanna. He may be just about to hit a 6 week growth spurt and he needs more fluids as he is having cold. His behavior sounds normal although I agree with you that you would expect your breastfed baby not to have a cold.
As for your diet, I don't think this affects his nursing pattern. Are you eating meat, vegetables and fruit and drinking enough water? As long as you are getting enough nutrients in your diet your supply should be ok and he should be getting quality milk. In my first weeks postpartum I was mainly eating rotiserie chicken, bread, grapefruits and oranges and drinking galons of water. There are some non-diary breastfeeding moms who may have some extra thoughts for you.
And I wanted to tell you, it is the toughest now, after he is through the growth spurt, it will get easier. His cold is probably messing things up, as soon as he recovers completely you will have some break. <<<HUGS>>>