Well... there is two kinds of weed, indica and sativa. The indica is that one which gives you that mellow, relaxing, couchlocked stone. And the sativa is that one which gives you the gigly, energetic, spacing out high. Most of common weed is a mix of this two kinds, so the effects are a bit of each one.
But high-quality weed may be a "pure" strain, only indica or only sativa... from what youve described, im almost sure that your last highs were from a pure sativa, so the restlessness, the "pins and needles", the heart racing and so...
Also, as you spent some time without smoking, your tolerance was almost null, so you felt the effects much more strongly... The first time i smoked, i felt some effects for some 2-3 days after smoking it... its pretty common when your tolerance is too low.
Im almost sure that your feeling of your heart beat and the "pins and needles" are due the increase of the sensitivity caused by weed... the sativa strains can make all your senses FAR more sensitive, so its possible to see, hear, taste, smell and feel (by touching) things that you wouldnt if you were sober.
So... there is nothing to worry about. In fact, my advice would be to enjoy while your tolerance is so low, cause after some time smoking you LONG for a high like yours... Also, if you want to relax, try to get some indica... or then make some drink/food with this weed you have.
And keep toking! :thumbsup::stoned::rastasmoke:

EDIT : The weed was NOT laced... its the first thing people thinks when hears about effects like yours, but laced weed is a very rare thing... Fuckin damn good weed is FAR more common than laced weed...