I started a job two weeks ago and the3 second week I got strep throat and was told to take the week off with a doctors note to prove it, I called the super and told him what was going on and he said to come back when I was able too, then two days later I heard from a fellow crew member the super was mad at me for not calling in everyday, even though I was specifically told I did not have to, so I started calling in everyday after that, and now I hear I may be getting fired because of it, is this possible in a non union job?

You are likely what is called an "at will" worker. You can be terminated for no reason at all at any time. However, you spoke to the super directly and he did not seem angry. A 3rd party is telling you different, this is called an unsubstantiated rumor at this point. Next time you call ask the supervisor what he wants you to do when you are ill. I would not expect this last string of absences to be covered under paid sick leave uliess that was stipulated to you in writing when you were hired, that your benefits include paid sick leave and start immediately

At the third week, most likely even with a union job you could be fired, many firms have a NO absent policy doing a probation period,

But in at will states, yes they can.

Well if you are in a no fault state then absolutely. Usually employment starts with a probation period. I think it is up to your boss who has a right to be frustrated about the situation your fault or not. Don't listen to gossip is my advice. Get better get to work and do not sweat it until the manager talks to you. You will have a chance to explain do you really think the boss told your co worker you will be fired? As long as it does not become a norml thing he may keep you. Stop worrying and get to work!