Still constipated

I've continued to breastfeed, I've given baths, I've rubbed his belly, I've done bicycles, my 5 month old still hasn't pooped in a week now. He's getting more and more gassy and they're been more potent so I think something may be brewing but is there anything else I can do? He seemed fine before, but now he'll get into fits where he's incredibly uncomfortable. I gave him a bottle of formula ONCE (last Saturday) and now his stomach is telling me to go to hell.