Hi Kels
This exact thing happened to us, too. Same age, same weight, everything. It was true, he was hungry and the milk wasn't enough for him any more. So what we did, we went to the pediatrician and she said don't start solids yet (as we have increased allergy risk in the family, too, eczema, hayfever and asthma) but put him on hungrier baby milk. In Germany stage three milk says four months onwards on it, I don't know how it is at your bit.
I would definitely ask the doctor, he may even tell you to give him rice cereal at night (mixed with formula) as this isn't really an allergen. But it may only be a growth spurt.