1 The lymph nodes in the groin (femoral or inguinal lymph nodes) may swell from an injury or infection in the foot, leg, groin, or genitals. 2  In rare cases, testicular cancer, lymphoma, or melanoma may cause a lump in this area. Glands can also swell following an injury, such as a cut or bite, near the gland or when a tumor or infection occurs in the mouth, head, or neck. 2  Glands in the armpit (axillary lymph nodes) may swell from an injury or infection to the arm or hand. 3  A rare cause of axillary swelling may be breast cancer or lymphoma.
Gastroenteritis, also known as infectious diarrhea, is inflammation of the gastrointestinal tract that involves the stomach and small intestine. Signs and symptoms include some combination of diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydration may also occur. This typically lasts less than two weeks.
Diarrhea is more frequent and more liquid bowel movements than normal. There are many causes. Diarrhea often is caused by an infection with bacteria, viruses or a parasite. Bacteria cause diarrhea either by invading the intestine or by producing a toxin that makes the intestine secrete more water. When the diarrhea is caused by food contaminated with bacteria or parasites, people often refer to this as food poisoning. Other causes of diarrhea include: Irritable bowel syndrome, especially during times of increased stress. Side effects from medications, such as antibiotics and magnesium-containing antacids.