Hello,
You need to do Body Composition Analysis(BCA). This is available in the various gyms. Depending on the results of BCA I will guide you further. I need to know your eating pattern and food habits, exercise pattern, medical history if any, your lifestyle etc. Then only I can guide you to solve your health issues.
Next Steps
Get your BCA done as soon as possible and contact me personally through Direct practo consultation. Sunday image of BCA if possible.
Health Tips
Some tips To avoid weakness-
(But let me make you aware that only following tips are not enough.)
Have one apple 1 hr before starting your exercise.
Sip water in intervals during period of your exercise.