Your mid-cycle spotting is more likely to be due to ovulation and so is the breast tenderness, due to hormones. Yet, persistence of the pain and radiation
to the shoulder and armpit calls for further evaluation. You need a proper clinical examination by a specialist, a complete hormone profile, blood counts, urinalysis
and a trans-vaginal sonogram to assess the situation and plan further management. If you are euthyroid with the current dosage, this may be continued. Please maintain a healthy weight and a healthy diet. Hope this helps.