What Causes Pain In Breasts, Sensitive Nipples And Blood After Urinating?

A few weeks ago my boob started to really ache for a few days & there was very strange nipple sensitivity feeling that would come and go, but the ache was constant - after I started my period the ache in my boob went away but about a week of being off my period, After urinating I noticed a tiny amount of light pinkish blood in the toilet & on the toilet paper-this happened a few times throughout the day(which is today actually) & now I m experiencing thick pasty brownish discharge. No odor really, maybe a slight one but it s not foul. I m worried, also I ve been experiencing chronic back pain for months I don t know if they re related but any information is greatly appreciated. I m 20 years old by the way.