Yep a docs visit is very much needed! In the meantime, before you feed, use hot towels or flannels to make a hot compress on your boob and massage gently as you've been doing towards the nipple. The heat will ease the tenderness and help with the blockage. Caught early mastitis shouldn't affect feeding. Hope you feel better - take some paracetamol for the fever.
Blocked duct or start of mastitis, I'd say. I got this all the time. You need to clear the blockage. Feed as much of it as you can, starting with that boob every time until it is clear. Massage while you feed if you can. I also found hot water in a disposable nappy applied to boob then massaging and pumping after feeding helped move things along. You can feed pumped milk to baby - even if mastitis, is just a bit saltier than normal, apparently.
Keep an eye out for your temp rising/ sudden flu symptoms as that could be mastitis which needs seeing by the doc.
And maybe go to a breastfeeding support session to get them to check your latch (something I never did, hence repeated blockages).
My boob is so sore!! Not the nipple my actual boob all down and under my right side, feels so tender like a bad bruise, it was really engorged and lumpy so my 6wk old had a super feed from it and Ive kneaded it so doesn't feel as lumpy but ouch! Hurts when I stand or touch it. I've also started to get little pains like stabbing/shooting pains across both nipples. It was all going so well! Any advice?