As mentioned above...
Throwing a couple of innings two days in a row may not be ideal depending on the number of pitches - but it should be something that you can do if necessary.
If you do move on to play in college, you are going to be expected to throw a lot. Probably 6-7 days a week at some points.
If pitching one day makes it impossible to throw the next, you really need to get your arm checked out. You are probably aggravating a chronic condition, and that isn't good for your long term health. It could be a mechanical issue, overuse, or even random bad luck - but whatever the cause, it needs to be addressed.
Keep in mind that you are paying a lot of money to attend some of these camps/showcases. Don't make it a poor investment by limiting what you can do, and who can see you do it.
Worst case scenario - a coach that had some interest on day 1 is told you aren't able to pitch on day 2. If you can't make it through a 2 day camp, is he going to think you can make it through a months long college season?