If the above doesn't help, lemme give you my niche chronic hand pain experience advice.
Numbness can also be due to a lack of strength, so doing strengthening exercises might help. I can't really draw with a pencil anymore so I have no idea what exercises may be suitable for you. I can only generally advise wrist and arm curls and resistance exercises for your fingers (think thumb wars with yourself).
It can also be from coldness/poor circulation. My circulation is shit and my hands have turned blue and numb before (but if that happens to you, its not a normal thing and you should get it checked out). I have a lot of heating devices handy whenever I'm drawing cuz my hands get cold fast.
If nothing here helps, please seek professional help. Better to catch an issue earlier than later.