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You have two main concerns.
The weakness is not due to low blood pressure. The low blood pressure can lead to dizziness and inability to stand as described by you. For that try to maintain hydration with lots of water and whenever you feel dizziness take salted food and fruit juices. You can check your blood sugar level as well. For tiredness, I suggest you investigate with serum potassium, serum sodium estimation, serum TSH (thyroid stimulating hormone) estimation, CBC (complete blood count), liver profile, and kidney profile. You can revert back with reports.
For pain in the foot, avoid prolonged standing or walking. It is advisable to investigate with X-ray foot for further work up. You should get checked your serum calcium and vitamin D level as well.