I hate to ask this of someone with more experience in the forum than i have, but is it pharm HGH?
second did you ramp up to 5iu or jump right into it. 5iu may be seem to be a low dose but if it is pharm the side can be harsh.
to answer some of your questions carpel tunnel is typical, and water retention may be why you are getting the tingly feeling and stiffness. again may be from not ramping up slow enough.
As far as the dizziness and vertigo. I have never experience that so I cant comment on it.
just my thought. I have been out of the loop for a bit but thought I would add to htis