Dear Madam,
I would like to tell you that different individual respond differently to the same medicines. Reason for this is ayurveda categorises individuals in seven different bodytypes on the basis of predominance of dosha(vata,pitta and kapha) which we called "Prakriti". If a person's prakriti is pitta he/she will have more chances to have acid refux/heartburn.
Next Steps
Stop taking ginger tea for a while. also let me know since how long you are taking ayush decoction and in what dose? Medicine should always taken in prescribed format else it may harm.
Health Tips
Take one glass of milk with munakka(black raisins). It will solve your problem. Also if you want to know your prakriti do let me know i am specialised in this field. I have ascertaind more than 1000 patient's and healthy individual's Prakriti.