What to do with this lump?

For a bit less than a week now I’ve been coexisting with a lump in my LEFT armpit.
– It’s painful (appearantly incresingly) when touched lightly and with certain movements.
– It’s rather big, protruding now to the size of almost half a walnut.
– I’m male (most info I found was relevant to female conditions)
– I took my temperature only today and it was first 37.5 then 37.1
– I have two cats (as seems to be of interest) but when this thing rose I was away from them.
-I’d sensed some annoyance in my armpit for maybe ½ weeks before the lump appeared. (Can’t be specific as to what I felt. Maybe I would’ve described it as a “swollen and hardened vein/artery” but very slightly.)

I’ve been to a doctor and am waiting for test results in 2 days. But I want to know what I can do in the meanwhile, and what to expect potentially.

Thanks,
and yikes..