Has anyone formula fed and breast fed at the same time?

C

I’ve been breastfeeding / pumping for my 3 week old, and was pumping 8 oz per pumping session so I had a pretty heavy supply! Now I’ve had a cold for a week and when I first felt it coming on I was exclusively breast feeding for 2 days without pumping just because I could hardly get out of bed.... Now I’ve been trying to pump for 3 days and can only get 2 or 3 oz per pumping session and I’m worried I’ve ruined my supply, or maybe it has to do with me being sick? Would it be back to feed him formula for the time being until my supply comes back? I will of course keep trying to pump and still feeding him but he’s constantly feeding off of me way more than usual and I’m pretty sure it’s because he’s not getting enough from me! But the thought of giving him formula makes me feel like a failure and I’m scared it will mess with his digestive system switching to formula for the time being! Has anyone switched for a short period of time and had no issues?