Fatigue, anxiety, heart palpitations.

Have fatigue, anxiety, muscle pain, heart palpitations, heartburn,pins and needles feeling etc. Have had b12 deficiency thrice in the past 6 years. Had taken injections each time and got better but issues come back. Doctors did not warn me of staying careful about this deficiency as it can come back. Last year February got GERD. Took a lot of antacids and had to depend on them everyday. So saw a doctor who asked for a b12 test. Unfortunately i started taking b12 injections before getting tested . My stomach is a lot better now but all the issues come back as i stop taking injection within a week. I am always tired and have no interest in doing anything. B12 has destroyed my life. When i look back i realise these symptoms started 8 years back. I can't help but think b12 has caused permanent damage to my body. Please let me know if there is any hope for a normal life ahead.