Is there any reason either loestrin or amitriptyline would cause tenderness on the side of each breast? i still have 2.5 weeks until my next period.

Possible : Birth control pills have estrogen and this can cause breast tenderness for some. Since yours is specifically located on the side of both breasts I am suspicious that this may be from a poorly fitting bra. If you have gained or lost weight recently this can make a previously fitted bra be uncomfortable. Just an idea. An exam by your doctor can evaluate the breasts for any abnormalities.

Yes: Both drugs are known to stimulate breast tissue. Loestrin due to its estrogen effect on the breast and Amitriptyline has been reported to cause galactorrhea (artificial lactation as a drug effect). You should discuss this with the doctor prescribing these.