Swelling and muscle spasms after stroke are fairly common, but not on the side unaffected by the stroke.
The swelling on the side of the stroke is usually caused by
a combination of lack of movement and lack of neural control of the small blood vessels in the arm and/or leg. I always warn people, however, that another more dangerous possibility is a blood clot in a vein of the immobilized arm or leg. Best to check with your doctor about getting an ultrasound to make sure there is no clot in the veins. Otherwise, the best way to treat the swelling is by a combination of compression devices (tight stockings and/or tight sleeves) and by elevating the arm and leg, particularly at night, by placing them under pillows.
As far as the spasms in the left arm are concerned, that is not a normal symptom after a stroke. The side opposite the stroke should not be affected. Best to get checked by your doctor. That could be from a second stroke that occurred at the same time as the larger first stroke, or by medications that were started after the stroke - among other things.
I hope that helps.