Hi
Welcome to the forum!
A patch that looks like blood or blood bubble at the back of throat is generally due to pharyngitis or inflammation of the pharynx (part of the mouth cavity seen behind the tonsils). This also causes difficulty in swallowing especially if this also involves the upper part of throat.
As SurgiMenopause mentioned, a sore throat persisting for so long should be investigated. It could be GERD or gastric reflux or allergy or viral. Warm saline gargles, anti inflammatory drugs and anti-allergics help control the symptoms. Drinking hot soups, herbal tea and warm lemonade also helps.
If symptoms persist you should consult your PCP. Please let me know if there is any thing else and do keep me posted. Hope this helps. Take care!
With a sore throat for that long, it's worth going into to a competent md and have them take a look-see. If they feel it's necessary, they can culture for infection. Did you know that GERD (acid reflux) can also cause sore throat?