Very worried

Hi, about a year ago I noticed a red patch/rash on my breast, it was close to the nipple area and about 2 inches wide ,but spreads around the nipple area After showering it would be very pinkish/red ,whine cold it's more purplish. Then a few months ago I noticed a slight dimple under my breast, very small but visible, I decide to be brace and see the doc, he did see the redness but not the dimple ,but he referred me to the symptomatic clinic, unfortunately I think the letter got lost in post because 2 months on I hadn't been called so I said it to my dr, he gave me a copy of the referral letter to post , I was called within a week. The dr at the coinic seen the redness and dimpling and sent me for a mammo and an ultrasound, the mammo was clear and during the ultrasound the dr pointed out the was some kind of infection as it was showing on the ultrasound , he said it was more likely to be a shin infection than a breast infection, nothing else showed up, I was asked to return in 4 weeks which I did yesterday, the dr literally look at the problem breast and acknowledged the slight redness( it varies in colour dept depending on conditions,e.g. Hot cold ) he also acknoledged the slight dimpleing . But he couldn't feel any lumps so he sent me on my way, now I'm still worried, I had read up about inflammatory breast cancer and it's very hard to diagnose, and sometime doesn't show on ultrasound and mammos .i am so worried that it has me missed.i have quite large breasts and I have noticed the affected one dose on occasion seem to get bigger ,also the rash doesn't disappear j,if it showed on an ultrasound dose that not imply there is something there ? What should I do? I haven't been told what the rash could be ,I'm 43 and I'm really worried something might have been missed.please advise