Hi Maru Licious,
I have read your question,
, weakness, are an effect of gastric problems and sometimes psychological problems.
With out physical examination and medical history it is not good to come to any conclusions.
You need not worry much , I suggest you to take good nutrition and healthy food , and get relieved from any tensions you have cause physical weakness is less effective than mental weakness.
I recommend you to practice meditation
twice (early morning and in the evening ) and think positive, let me tell you half of the issues in our body can be cured just my positivity.
Weakness, pains , Fainting
or passing out are commonly experienced by the people with diabetic history or malnutrition
and fasting people .
Alternatively I suggest you to do consult a physician nearby , with your medical history , to get assured guidance .
I hope you get well Soon ,