Mastitis/drop in supply

I was diagnosed with mastitis a couple of days ago and have to take an antibiotic 4x/day.. I have been pumping as often as my baby eats, drinking mothers milk tea and eating lactation cookies and oatmeal every day, and my milk supply has dropped. I am struggling to make enough milk to satisfy my 4 week old son and I really don't want to have to supplement with formula..any advice/support would be appreciated!