Well dietary factors can include eggs are a source of cholesterol, I think so does milk and dairy products. But even so in vegan diet some cereals (including sugars), oils and seeds contain more than trace amounts of cholesterol, though may have very little effect. Then again as suggested there could be a metabolic problem here, one of which is diabetes.

Cholesterol is generated directly from the food sources but can be synthesized in the "endoplasmic reticulum" … this is a homeostatic approach to keep the cholesterol level balanced and to avoid dangerously low levels of cholesterol (hypocholesterolemia).

So (in theory) sustained periods of undernourishment may have tricked your body into producing high levels of cholesterol, and these may have remained when you return to a proper routine of eating which is why a balance diet is not about limiting intakes of certain foods but keeping nutrients in regular balance.

"Genes" is too simplistic an excuse, there are environmental factors such as stress and hormones to factor in too. There are plenty of medical arguments to causes and solutions, you may have to have a conversation with your doctor to see what's right for you.

I would (personally) also seek to check if the monitor was calibrated properly or get retested to see if you have returned to normal.