i had the same chest discomfort / pain for nearly 3 months now,i did 2 stress test,echo,thyroid test and full blood count..the cardiologist say its fine..the only thing now is i have an holter set up appointment on march.its very frustrating..i think anxiety can causes this chest discomfort and pain too.
It is very common for you to see your clothing on your chest move during palpatations....thats why i never looked down...the feeling was bad enough! If you're having these opisodes thru out the day you need to make an appt. with a heart doc especially if its going on for 3 weeks and if it feels like its getting progressive or happening more and more frequently.....if its enought to bother you.... time to make the appt. In the meantime stay away from coffee, colored sodas, chocolates, energy drinks, make sure you aren't overtiring yourself and not getting enough sleep and try not to stress it because stress can set it off too. It may very well pass by itself but if its coming more frequently and more often i'd bet it won't and then you need to have an EKG/ECG done to get it diagnosed. Keep us posted....
Sound to me like you need to get checked by a doctor.
At your age it is most likely something that will pass on its own, but you don't know and seeing a doctor is the best advice you will get.