Last time I had a physical I was deficient in vitamin D. Sure I still am.
Low vit D is BAD
Leads to other deficiencies
Thyroid problems
Required in testosterone production
Linked to depression (I felt SIGNIFICANTLY better after learning I had a vit D defiency and started correcting)
Most likely low or high calcium
Low phosphorous
etc.
You should go to your doctor for a treatment plan to correct your defiencies and see if the low vit D caused other defeciencies
Vit D defiency is a major problem along with other defeciencies people probably don't know they have e.g. magnesium, thiamine, zinc. etc.
You can't just raise it to low normal either, it has to be in the upper optimal range for vit D but you will notice you will feel better and better
Taking vit D has consequences so also research the cofactors you will need alongside it to avoid creating other deficiencies
Check EVERYTHING autoimmune, thyroid, genetics, all vitamins and minerals, amino acids etc. any slight imbalance can make you feel depressed
If you correct all of that, surround yourself with good energy, and still feel depressed I would seek a professional
You have to pour all resources and money into this now while you can because you don't want this to linger and ruin your youth and prime (now to about 45+ for a man?)
Disaster and life can happen at anytime and you don't want to be
1) depressed
2) not have the resources to address 1)