Odd changes to heart rate with body position.

[Andyxvxo]

Hello all. I am a 32 year old non smoker with no previous medical issues. Lately I've been experiencing some odd heart rate changes. My heart rate at rest laying down (when I'm calm and not stressed can be as low as 57 bpm. I'm by no means a well conditioned athlete... In fact I am out of shape and de-conditioned if anything. When I stand, my heart rate shoots up to the 110's or 120's. It will sometimes normalize a bit (down to low 100's) but won't go below that even though I'm relaxing standing still. Very light exercise causes it to go above 160. If I go into a crouch position. It falls rapidly, back to the 60's or low 70's. Then, upon standing again, shoots back to over 100. This has been happening for the last few months. Makes it very hard to get anything physical done. Sometimes I experience a brief arrhythmia (feels like a skipped beat or pause, then a hard sudden beat) but it only happens sporadically and without a known trigger. It can happen at rest, sitting standing or lying down. I was wondering what could cause me to have borderline bradycardia at rest laying down and tachycardia standing without activity. I know POTS can cause this (haven't been diagnosed) but what concerns me is how I can bring about such abrupt changes based on body positioning alone. These fluctuations happen rapidly.
My other symptoms during this are extreme fatigue (cannot work or do prolonged housework most days)
Cold extremities (especially feet)
Muscle weakness with limited activity
Brain fog and confusion- difficulty focusing and concentrating
All this had a definite onset around mid October last year with no seeming trigger and started mild and has now worsened to me being very inactive. I used to go to the gym several days a week and hike for miles. This is destroying my life.
All my blood tests/labs seem to be normal except for a TSH level of 5.48 last month. (Waiting on results of retest I had last week) I just got done with a 24 hour holter monitor and will be awaiting those results. Even the tech who did my ekg said the changes she saw laying vs. standing vs. crouching were very odd. She did ekg snapshots in each position. But what could be causing this?
Any help or insight is greatly appreciated.

[Jerry_NJ]

Some of your numbers sound okay to me, then reading on I am lost for any connection to my experience and reading.  Best to see your doctor, seem worth it to me.  Sorry if I skipped over mention of a doctor,

Some of the dizzy/confusion may be side effects, are you on any prescription or home made herbal medications?  If you list, I can not intrepidity further, raise the issue only as something you may need to consider.

Good luck,