Mastitis - when to speak to the doctor

I think I may have mastitis - I've been experiencing suddenly very strong flu like symptoms (pain and soreness in miscles and joints all ovrr my body, headaches) but did not put 2 and 2 together until last night when I also got chills and had to put on my winter PJs and blanked to feel warm (yes, in THAT weather). I took ibuprofen and felt better, today I am not feeling great and feel very sore all over my body but the ibuprofen seems to work and this morning I examined my breasts and found a lump. It is a bit sore to the touch and when I feed, but apart from that it does not really bother me and baby feeds well on that side. It is not painful unless I touch it, does not feel hot and is not visible. We have not had any latching issues, engorgement or anything like thay, so I am at a loss why this is happening. So do I wait a couple of days to see how the ibuprofen works, or do I speak to GP today?