All kinds of bugs in the dream represent inner troubles, troubles encountered in life and so on.
The worm you described will suck blood, which means something harmful to your energy.
And it can't be completely solved, and it will explode as soon as it is pulled, which means it can't be removed at one time.
The tail will stay outside a little, which shows that you can clearly realize the bad influence of this problem on yourself.
I think I'm still worried about my health.