do not patch it. yes, you need to see a professional (optometrist or ophthalmologist). do not use any visine or naphcon-a or opcon-a or anything that "reduces redness".
my guess is you have a subconjunctival hemorrhage, but thats just a guess based on your description. if that were the case, it wouldnt be a big deal, but it may mean you could possibly have other systemic problems (like undiagnosed hypertension, for example)