First I want to know in what medical condition you used this dexamethasone and how much mg you in take since how long you are using ?and while you are facing side effects First you need to stop the medication immediately and you didn't mention the name of ayurvedic herb that you used saying that contain steroids and no ayurvedic herb causes weight gain with in one day for sure may be some times the medication causes allergy like red face you mentioned but not the weight gain with in one day
And my suggestion is you need to consult a doctor with your complete case history then you can get the correct and proper treatment for the problem you are facing ...
Next Steps
need to consult a doctor with complete case history
Health Tips
don't be panic symptoms will slowly subside once you stop the medication if you have the symptoms by using the medication but the symptoms what you are facing is due to your health condition how can you distinguish between the problem you are facing is by the medication or due to your health condition so better to consult a doctor with your complete health condition case history...