Heart Spasms, Twitching In Shoulders. EKG, Blood Work Normal. Suggestions?

Yesterday afternoon, I felt like I was having 'heart spasms'. Like 4 or 5 quick spams of the heart muscle in a row sporadically through the day and night. I went to urgent care. Normal EKG (though I didn't have a spasm while taking it), normal blood work, dr. listened to my heartbeat and said it was OK. Then this evening they started again. Over the last few weeks, I've experienced them lying down in bed in the evening as well on a few occasions. I would definitely describe the feeling as spasms or twitches or even a jolt rather than a palpitation. And on a couple of times, it was so intense that i felt my shoulder twitch/spasm at the same time as a result of the spasm in the left chest. No pain involved whatsoever though. Curious as to a doctor's thoughts... heart related and thus a need to see a cardiologist OR something unrelated to the heart?