I bite my nails and now my thumb won't stop hurting?

Yes I know biting nails is a terrible habit and I bleed a lot from it and it causes lots of pain. But, the pain in my thumb won't seem to go away. And it is immense throbbing pain. It's very sensitive as well and I haven't even bitten at that nail for days. Could this be something serious?
I bite my nails and now my thumb won't stop hurting?
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