Two simple home remedies to try:
1. Cold showers
2. Apple Cider Vinegar (ACV). Have a teaspoon or two in juice.
Also, I reckon first try taking up some exercise like swimming.
I once fasted after getting some bad food poisoning and had an interesting experience - after my digestive system was cleared out I felt incredibly at ease, all that tension and low level anxiety was gone. My mind was also bright and creative. My point is the digestive system has unexpected effects on our emotions and even our immune system.
A "fast" in which you only eat fruit, water or fresh made juice is a good way to start, but you need to be willing to go at least 4 days.