19-year-old male with severe ass pain & bloody stools?

Discovering a worm in your stool might be due to a parasitic infection. Parasites can enter your body through contaminated food, water, or surfaces. Consult a doctor for diagnosis and treatment, maintain good hygiene, and practice food and water safety. 

It seems that you have an ailment known as an anal crack. This condition is characterized by cracks in the skin around the anus, which can lead to blood and/or injury in the rectum. This may be from being constipated, having diarrhea, or simply surviving hard stools. To relieve the pain and the healing process, you should see a dietician who will give you foods rich in fiber. Also, a glass of water every day and the use of over-the-counter creams to cover the corroded area can be used to help ease the pain and promote the area to heal. For sure, the area troubles you, however, you are urged to seek help if the techniques have failed and no improvement has been noticed.

Infections or certain medical conditions are the possible causes of diarrhea. When you are already taking rifaximin and still not feeling better, it is crucial to communicate again with your doctor. They can go for more examinations or try other methods to cope with your situation.

These issues might be due to problems with the pelvic floor muscles not functioning properly during bowel movements. Pelvic floor rehabilitation could help by improving muscle coordination and strength in the pelvic area, potentially aiding in better bowel control. Another option is biofeedback therapy, which uses sensors to teach you how to coordinate your muscles during bowel movements. Discuss these options with your medical team to find the best approach for you. Additional diagnostic tests might be needed to understand the situation better. 

After a gastroscopy, do not take too much force on your body. The glass of wine can hurt your throat because the numbing spray has already worn off. You might feel some mild discomfort or have a little acidity. It's better to wait one or two days before relishing that wine.