If there's nothing else wrong with you (i.e., no cardiovascular disease or overt circulation problems), this may just be a consequence of an over-aroused sympathetic nervous system response. This is the "fight-or-flight" response in which adrenaline levels increase (along with other hormone levels), leading to faster heart rate, vasodilation/constriction, etc. causing different circulation patterns (blood rushing to or from extremities). The sweating also supports this. Are you an introvert? If so, chances are your body will have a lower sympathetic threshold.
No medical expertise here, but I've had the same problem for years and have just learned to live with it. (Sometimes it may get better with age, but there's no concrete evidence for this.)