That's interesting.

I'm most definitely not an expert but from what I can find out, It does appear that tomatoes can cause small red spots in one's poo.  This may be what you're seeing but I can't say for certain.

I think that if I were in your situation I'd report this to my GP and ask for fecal test.  This means you have to put a sample of your poo into a jar!  This isn't as difficult as it sounds -just spread a double length piece of kitchen towel across the loo, holding it in place with sellotape if necessary, then drop a poo onto it.  Use the supplied spoon to grab a sample, then flush the whole lot away for clear up. 

When the result comes back clear, which is highly likely given your age, then you can breathe easy.