Hello and welcome to NeuroTalk.

Tics are not habits. Often they are erroneously called nervous habits but that is not correct. Tics are involuntary or "unvoluntary" but there is usually a sensory component involved, especially in adults, and that's called a premonitory urge.

There can be an overlap between compulsive behaviours and tics. Lots of people have compulsive behaviours but they don't have tics. It's quite complicated.

Do you have any other behaviours such as on this list?
Brief list of common tics (pdf)

Do you have OCD?

You typed "I have to crack my knuckles". Do you mean you feel an urge to crack your knuckles and it builds up until you must do that? What will happen if you don't crack your knuckles?

There are also stereotypies which are more ritualistic or repetitive but they usually begin in early childhood.

Basically it could be many things. You should talk with your doctor if these behaviours are interfering with your daily life. The problem with continuous joint cracking is that it can really damage the joints.

take care there