I've been prescribed levothyroxine. but it gives me bad anxiety, panic attacks, palpitations. could my heart be bad? what can i do about anxiety?

Check with your MD: You need to check with your medical doctor or endocrinologist as your palpitations may be related to the therapy, you may be taking more levothyroxine and may need dose adjustment.That in turn may be giving you panic/anxiety attack you need your tsh, t3&free t4, checked and if dose adjustment or blood test is ok, you may get treated for panic attacks witth ssris and/or tranquilisers.

Have thyroid retest: Your thyroid should be retested in case the dose is too high. Your heart is likely fine, but talk to your doctor about your concerns. There are different forms of thyroid as well. Your dr should know how to treat anxiety. See a psychologist for therapy and a psychiatrist if your own doctor prefers to refer you for medication. Get good sleep, exercise reasonably, keep a healthy diet and consider yoga, meditation, and or acupuncture as alternatives.