Looking for answers - Breast Cancer and Thyroid

Good Morning! I have stage 4 breast cancer and am currently on oral chemo of Ibrance 100 mg and letrozole; have been for past six months. Good results on spots - per PET scans they have reduced to 2.1 from 5.7, will continue on these meds until I can no longer tolerate or cancer does not respond.

Had an extremely difficult three months last summer body aches, fatigue, (to the point of spending weekend sleeping) along with hot flashes, shortness of breath climbing stairs or working in barn. Weight climbed to 160 from 145. Was 130 at start of chemo in 7/2014. Only taking Tamoxifen at that time. Last chemo cocktail was January 2014.

Due to issues (at time thought I was cancer free) Had blood work done by MD in August 2016 - showed TSH 1.2, FT4 free 1.27, T3 total 163, TSH 1.20, T4 Free 1.1 and T3 Free 3.4 by MD. Dr said all normal.

Saw Oncologist August 2016 for 3 month ck and tumor markers CA 15.3 & CA 27-29 were 44 and 46.4 respectively. Pet scan showed 2 spots over 5.4 in right axillary & supraclavicular nodes.

Switch from Tamoxifen to letrozole and Ibrance chemo med handled well but body aches, fatigue, (to the point of spending weekend sleeping) along with hot flashes, shortness of breath climbing stairs or working in barn hit again mid-January and symptoms are again unbearable. Basically spend weekends trying to have enough energy to last work week.

This is all just general background info. Have discussed sympthoms with Oncologist and blood work does not show anything to explain issues.

Oncologist ran TSH again in April 2017 - test came back at .76

Here is my question - Is that change in TSH normal? Oncologist tested TSH in 2/2016 and it was .63, so .63 then rose to 1.20 then back to .76. I feel horrible. I need help. I have learned that I have to be my own advocate. Looking for answer to horrible summer and horrible last 4 months. Have read info on TSH, T3 and T4 but do not fully understand.

Thank you for your time and any answers.

Thank you for the reply. I have been on a Vit D supplement due to it being low for the last four months. I am on what I think is a healthy diet. I cannot eat any fruits or veg that are not peeled due to low counts so no lettuce, strawberries, etc. Only eat venison instead of beef, lots of chicken. How do you check iodine? Is it a special test? My tests show sodium, potassium, but not anything I can identify as iodine. My cancer is estrogen positive. I will check into the iodine test with my onocologist. Thank you for your suggestions. R