My heart starts racing randomly for some reason. I don't have any chest pain or anything but my heart is racing. I'm not sure what it's from?

Heart racing. Definitely of concern. Start by logging your symptoms and specifically circumstances when it happens, time of the day, completed/ about to start activities, mood, etc. Try to feel your pulse at the wrist and get a rate/min, have somebody else count and confirm also. Reduce as much as possible caffeine containing drinks. If pulse consistently over 120/min talk to your doc for a visit. Bring log.
Many possibilities. Could be due to many things: anxiety and stress; true heart rhythm abnormality; overactive thyroid among many others. Tests I would do would be a thorough history and physical examination, an Echocardiogram (ultrasound of the heart), routine EKG, blood work including a TSH to measure thyroid function, and a 24 EKG Holter monitor. That combination is more than likely to yield a diagnosis. .