I am no expert but I found solids are harder for babies to digest and so can make them constipated and more unsettled if you start too early. Ignore other people's well meaning comments you'll go crazy if you try to follow it all anyway!! Breastfed babies feed more often because it is much easier to digest than formula, bubs could be having a growth spurt where they feed heaps for a while then settle down again. Just relax(easier said than done with #1 I know) and be confident that you are doing a great job and thatyour milk is making a healthy baby. (If his weight is going up and he has plenty of wet nappies he's getting enough milk) Some people seem to introducing solids will magically solve any problems. I think a lot of older people have trouble coping with the fact that solids are introduced so much later these days.Even 15 yrs ago when I had my 1st we gave them at 4 months which didn't make her sleep through the night or anything either!
Hope this ramble has helped a little bit.