Welcome to HCM
You have not mentioned your height but it seems that you are overweight and started exercising recently.
If you have pain in left arm it may not be cardiac but still it is prudent to check it with a ECG 12 Lead and if it is normal get other medical test befor you take up weightloss programme.
A complete check up with BP and other system alog with investigations :
Complete Blood Count
, FBS & PPBS,
, X ray of cervical spine
T3,T4 & TSH, A X ray chest, 2 D Echocardiography
, and TMT( Tread Mill Test)
If every thig is fine and you can take care of diet and exercies you will certainly able to lose weight .
Best of Luck.