I am 20 yrs old and I keep noticing my heart beat feels like a sudden "thud" its becoming more frequent... Resting heartrate is also on the fast side?
PACs or PVCs. Extra heartbeats that come from outside the heart's normal electrical system can cause a sensation of skipped or strong heartbeats. These can come from the top chambers of the heart (atrium, premature atrial contractions, pacs) or the bottom chambers (ventricles, premature ventricular contractions, pvcs). Wearing a heart monitor can help determine if this is happening, it is usually not serious.
Hydration. One common reason for increased heart rate is dehydration. First make sure you are drinking more water (goal is 1/2 your body weight in oz). Limit your alcohol intake, and get plenty of rest. If this does not improve your symptoms, then you need to get an ECG done by your doctor to make sure your heart rhythm is normal.