I had hellish mastitis took about 10 days in the end and three visits to the doctors!
Firstly I was given antibiotics - the wrong one (well not wrong as such, but not the 'best' can't remember what they were now) but OOH doc who to be fair came out in the middle of the night when I felt like I wanted to die! not melodramatic at all
Then 3 days later when I felt worse not better DH booked me an emergency appt with doc, who gave me supposedly better antibiotics which he said to take alongside these other ones as sometimes it could take too types 
Then a few days later again when I was exhausted, felt like shite, guilty the lot I burst into tears on HV and then receptionist, they booked me appt with amazing doc , she fit me in in her lunchbreak and was so sympathetic I burst into tears again (reached my limit that day!)
She was concerned that I might have an abcess so examined the breast and I could tell she was trying to massage / push out any blockage at the same time, was like deep tissue sports massage
she kept apologising as she knew it must hurt, but through my tears I was saying I didn't care if it helped! She told me she didn't think it was an abcess, but to go home - soak a flannel in really hot water, lay it over the sore part of the breast for as long as I could handle and masssage again, and keep doing it and she'd see me again the next day (again at the end of her shift) and if it was no better I'd be off to hospital for a scan... this lovely lady knew what she was doing - I did the soak / deep massage thing another couple of times and by the next day I felt human!
still shit / exhausted / bruised etc, but the horrid fluey symptoms disappeared like magic
She assured me it may have been that the antibiotics were about to turn a corner - I laughed at her! She had breastfed twins and had double mastitis to deal with so knew her stuff.... I now love and want to stalk her!