To toil or work hard, specifically doing strenuous physical labor. The term likely refers to the camel (camello), an animal known for enduring heavy loads and difficult work.
'We are going to Camellarle really early today.' 'I am camellando, I cannot go grab some beers.'
To work or be busy with a job or trade. A person who is chambeadora is a hard worker or a hustler (this is the standard informal term for work in Mexico).
I am chambeando, see you later. Let's go to the chamba. You have to chambear to pay the rent.