Hello, Your description may indicate blood vessels visible and if close to the surface they can appear purple. Her age and medical history would be very important to help with a diagnosis. Does she seem to have difficulty with control of her tongue and does it deviate to one side? Is her speech affected? How long has this been going on and have you noted any changes? She could have a muscle attachment under the tongue that restricts her tongue movement. A simple procedure to release the attachment could give her a wider range of movement and solve this issue. Biting the tongue could cause one sided inflammation. Swelling, a bump, discoloration and even an ulcerated area are all possible. Rinsing with warm salt water and gentle care with a soft diet will assist healing in this case. Avoid irritants such as acidic foods and liquids, spicy foods and keep a well-balanced diet. An excess collection of blood vessels could be of no concern or indicate a cyst, tumor or growth. Please look for additional signs of swelling, bumps and sore spots. A dental infection or other systemic disease should be considered if you find any of these signs increasing. Changes along the back border of the tongue should be Inspected. Additional information may be obtained from a blood test for deficiencies. Muscle and nerve health would be evaluated further by a physician if necessary. I recommend a dental exam with a clinical examination to be sure. You can try some anti-inflammatory medication to see if signs of inflammation can be reduced and make a difference. I hope you find this information useful and thank you for your inquiry.