Hi,
Welcome to Healthcaremagic,
After going through the available details it seems you have basically two medical issues.
First one is low blood pressure as 83/55 mm of hg is low and is symptomatic as you feel light headed and dizzy and supine position makes you comfortable.
If you are dehydrated then taking plenty of water and even increasing salt intake is helpful.
The other problem is low blood
Hemoglobin which is 10.4 gm/dl the cause of
anemia must be investigated and treated accordingly like any blood loss from the body.
I would suggest you to consult a Physician and after detail physical examination appropriate investigations like
complete blood count, Fasting blood sugar, liver and
kidney functions, urine and stool analysis and if required
abdominal ultrasonography and an X ray chest may be done.
Treatment would depend on cause.
Hope this helps.
Take care.
Good Luck.
Dr.Akhilesh Dubey M.D