Could Numbness In Left Hand Be A Matter Of Concern?

Hi, I am a healthy 18 year old and about 40 minutes ago I lost most of the feeling in my left arm and it has gone very limp/weak. Is this something of concern? I have not lent on it or recently woke up so there is no reason for it to be asleep . I have also been experiencing high BPM when excercising, sometimes reaching up to 234 BPM and am concerned this may be linked (although I ve not done any excercise today). Any answers appreciated, thanks!