I have weight loss due to digestion issues. How to gain the weight back?

Hello doctor,

I am suffering from digestion issues, mostly bloating, from more than seven months. While taking medicines, I was feeling fine, and once I stopped them, my symptoms recurred. My present symptoms include indigestion, constipation, improper motions, low appetite, weight loss, inability to gain weight, acne, anal itching, body aches, etc.

I have issues with my mind also such as lack of concentration, confusion and other problems. I consulted a neurologist who said my vitamin B12 levels were low. So, I took supplements. Now, after taking those medinces too, I do not feel much of an improvement.

In the past, I was affected by worms for around five months. When I took medicines for that, many of my problems got solved. But, digestion issues persist. I consulted a gastro doctor two months back. He said there were no structural problems present and prescribed Cadigut, Acta pro, and Folizorb. Once, I started to take those medicines, I felt good, and my weight improved. But, once I stopped those, the same problems restarted.

Now, I am on Acta pro. Before this, I never had issues with digestion. It all started with worms. After presenting this query, the doctor asked me to check for bacterial overgrowth in the intestine (SIBO), hydrogen breath test and asked to take probiotics. My appointment for the test is next month. Is there anything that I have to follow before the test? Please suggest which probiotic tablets to take.