Hello, Thanks for your query. As you are experiencing numbness on the lower lip, there are chances of any decayed teeth ( lower jaw ) which may present with pulpal infection which in turn may cause lower lip numbness. But still, visit to dentist for clinical evaluation is best which should be done as soon as possible. Afterwards, you can start with the desensitizing tooth paste but should be used for slightly longer period to get best results. Control release painkillers are also useful in such condition. I do hope that you have found something helpful and I will be glad to answer any further query. Take care