does vitamin b12 injections have any side effects Common & Rare of Potential Vitamin B12 Injection Side

At minimum, check metabolic panels, liver function, lipid profiles, and fasting glucose before starting and every 8-12 weeks during combination therapy

Pyo et al

Biochemical Pharmacology (2018) 2

Still it could be part of the problem in your situation

It upregulates genes involved in collagen synthesis (COL1A1, COL3A1, COL5A1), extracellular matrix remodeling (decorin, fibromodulin), and antioxidant defense (superoxide dismutase, glutathione peroxidase) while simultaneously suppressing genes associated with inflammation (IL-6, TNF-alpha), fibrinogen production, and tissue destruction (several MMPs)

I bought my injections with both b12 and lipo