I don't have too much advice, but i wanted to say that i got mastitis only once with DS1 who had a troubled bf journey, and then DS2 who was the perfect feeder and everything went wonderfully - and i got mastitis countless times with him, once even i had to go to the hospital day clinic for treatment.

Can someone come over and give you 3/4 hours rest? If you get it early it can improve very quickly. You might need ABs?