https://www.amazon.co.uk/gp/aw/d/B01JRLTP9E?psc=1&ref=ppx_pop_mob_b_asin_image These are really good to relieve the pain and to help with milk let down when your boob is really hard. They helped me when I got mastitis. It’s horrid but keep feeding and start on the sore side so baby has more chance of draining your boob x
Mastitis is the worst, I’m sorry you’ve had this so early on in your breastfeeding. With my first baby I used to get blocked ducts a lot, and having 2 hot showers a day really helped (morning and evening). And I found that feeding got a lot easier once we got past about 8 weeks. For the cold, try a nasal spray and a snot sucker - it’s a bit gross, but really does clear their nose. If you do that before a feed they should be able to feed more easily.