Drying up? 5-6 oz to 1-2oz pump

Hai! I was wondering if anyone’s dealt with one breast producing less? My left side pumps 5/6 oz but my right side struggles to get 1/2 oz. In the beginning I could pump 4/5 oz on both sides. My right side also has had this hard lump in it which feels kind of bruised. Now I tried massaging in the shower and hand expressing and I do get maybe .5 oz when I hand express but I don’t know what else to do. I have a drs appt Tuesday just Incase it doesn’t clear up and may be mastitis. Any tips or tricks are appreciated! Thank youu! ❤️