I was smoking weed at 65 after no smoking for 30 years and now my right arm has ache or spasm. Mi?

Heart Attack. Very unlikely to have an mi with right arm pain, pressure or spasm. But much more likely if your left arm was involved. Sweating, nausea, shortness of breath, you need to get checked immediately, especially if these accompany chest pain or pressure or left shoulder aching, pain, pressure or squeezing.
See a doctor. ..."weed" or not, don't try to find out what is causing your pain by coming to a web site. We can't answer that without seeing you, examining you, and knowing your history.