Sounds dreadful. Reminds me of the residual effects of Lyme disease.
It/they can be. Sometimes recluse spider bites can be intensely nasty, kill tissue for amazingly long periods of time, months, even years. Nothing good about them at all. A seriously bad bite can turn into a non-healing, painful, prone to infection area like a major bad burn that nothing works on. Profoundly bad news.
I had areas of exposed bone on 1/4 of my forehead and my left eye swelled shut for over a week.