Welcome to HCM
It can be due to local problem like joint inflammation
or arthritis but you need to rule out heart attack
which can also present with left arm pain. The pain of heart attack can be anywhere from the lower teeth to the belly button area. Be careful and get an ECG and consult by your Doctor first. If it is arthritis it can be treated after taking X-ray/MRI especially if there is tendonitis
or tear in tendon of shoulders as necessary. Stop eating junk food. Eat fresh green leafy vegetables like lettuce, palak, spinach as they reduce cholesterol
. Eat oats which is also healthy. Eating oily fish has been shown to reduce cholestrol
as well in some cases. Discuss this with your Doctor as per your laboratory tests. Drink 1-2 litres of water a day. Exercise by brisk walkig everyday to reduce cholesterol and keep fit.