I have no answers about the infection but can sympathize regarding the pumping and exhaustion and breastfeeding problems. I was never able to successfully breastfeed either of my kids and it depressed me terribly. I chose to pump and bottle feed for 6 weeks with my son and only 4 weeks with my daughter because it was nearly impossible to do it on a schedule once the second baby came along. I also had both of my kids via c-section.
If you fear your son is not getting adequate nutrition, it might be wise to supplement with formula but keep pumping to continue to build your supply while you work to get healthy again. However, breastfeeding is taxing on the body - like pregnancy - so if you're having energy issues, quitting one "process" might help ease the fatigue.
I think the question is what you want to do and what you feel right doing. There's no doubt that breastmilk is best for the wee one, but formula has come a long way too.