What Causes Constant Palpitations?

Hi, my situation is in regards to constant heart palpitations, here is how things happened, about 3 weeks ago I was smoking weed and it was very strong and I almost felt like I was going to pass out it didn t feel good and my heart was going crazy. Over the next few days I started to feel these hard beats but I thought they d go away but almost a week in they continued and then I wasn t smoking but I was around someone who was smoking and I believe I got a contact high from being in the same room and it got really bad and my heart was going crazy again I had a panic attack and I thought I was going to die I could barely sleep that night I had yo go to the bathroom many times that night. I have been belching and very gassy since then and I went to the ER a few days later and they did some tests an EKG and they did an x ray and they took my blood and urine and said everything was fine but I don t feel fine the palpations have toned down somewhat but it s still ongoing I also notice they seem to get worse after I eat it s been almost a month every day with this it s really been ruining my life and I don t know what to do because it s very uncomfortable