My tongue has been hurting for about 4months now, went to the dentist and they see nothing. what could this be? i noticed it hurts when my heart skips

Seek a 2nd opinion: Pain of tongue is can be a result of tongue inflammation. Causes vary from allergic reaction, yeast infections, local trauma, sjögren syndrome, vitamin deficiency (low levels of vit b12). I would also consult a cardiologist to evaluate your arrhythmia, and if there is any association of arrhythmia with a painful tongue.

Sore tongue: Glad your Dentist has ruled out an oral cause. Now you need to see a Cardiologist for your arrhythmia and an ENT to evaluate tongue/throat.