Vegetarians get low in B12... 7 yrs is a long time. You probably used up your stored liver B12, after 5 yrs.

Vegetarians also do not get methionine from the diet unless they eat eggs, and dairy.

Zinc is also a nutrient that is lost. Males lose zinc with semen ejaculation and can become low in zinc if no meat or seafood is eaten to replace it. Zinc is the mineral most likely lost by males, and iron by females. Some males may lose up to 5mg per ejaculate.

You need to get a B12 test, and it should be at 400pg/ml at least. (other countries have different concentrations reported so you need to bring that result here so I can convert it for you if necessary.)
Some doctors allow below that, but that is old old treatment, so if you are below 400 you should supplement at least 1000mcg of activated methylcobalamin daily on an empty stomach. This is quite inexpensive and easy to do.

Zinc should be measured with a blood test too, as its own level and also in the zinc/copper ratio.

Vit D needs measurement too, and magnesium. These are commonly low or deficient in adults today.

Thanks! I will be tempted to try supplementing with B vitamins anyway, because the alternative is taking prescription pain killers potentially for a long time.

you should get tested before taking b12 vitamins, to see where you deficiency lies.

That makes sense. In the UK I expect the NHS will give limited tests for free with long waiting cues, so I guess I will have to find a private nutritionalist or naturopath.

Stop taking all vitamins and minerals about a week before any testing, or the results may show artificial elevations.