Hi.. Can understand your concern.. As per your complain dark veins under the tongue is mostly a normal finding and there is commonly no pathology associated with it as everyone has appearance of bluish veins under the tongue due to their superficial nature of placement under the tongue.. Many a times there can be dilatation of veins known as varicose veins and can appear as large bruisings under tongue but it also does not cause any complication.. The other query which you have put up is small bumps under the tongue can be due to obstruction in the salivary gland ducts or the minor salivary gland obstruction can lead t spilling of saliva into the adjoining soft tissues leading to formation of small swellings or bumps.. They are mostly painless and rupture themselves and heals.. In case they are large and doesn t resolve surgical removal or laser ablation has to be done. At times the ducts of the major salivary glands gets obstructed thereby leading to back flow of saliva into the gland causing swelling.The exploration of location of stones and removal can provide relief.. Another part of your question is that pain in Jaw joint, it can be due to any injury to the joint due to blow or accident or some other habits like teeth clenching,teeth grinding or any high points in caps or fillings etc.. It can also be due to any arthritic changes in the joint.. I would suggest you to consult an oral pathologist and get evaluated as the treatment can be planned as per the clinical examination and required laboratory and radiological tests.. Hope your query is solved.. If you find the answer helpful please write a positive review and click on find this answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora.