Constant breast pain

Hello everyone I’m here just for some reassurance / clarification I’m not going crazy. 

for years on and off always had pain in my right boob, would normally come around period time, however since November 25 I’ve had constant pain, it moves, sometimes near nipples sometimes under armpit, sometimes above ribs, I’ve starting to feel a pull in my neck as well. Some days will be fine ish, then bad in evening , some days pain is 24/7, the best way to describe the pain is “ a heavy feeling” sometimes of nipple feels slightly itchy, there is no real routine to it.

i have been to doctors more times then i can count for, had numerous examinations and an ultra scan to be told it’s probably muscular  related I feel like because I’m young and ultra scan was clear I’m not being taken seriously .

 I have  awful health anxiety since having my little boy during lockdown, and this breast pain is consuming me. I struggle to believe I can have it every day and it not be sinister. 
please help.