Hello.
Thanks for writing to us.

Small cut by a fingernail is not likely to be so large so as the bone can be felt beneath it unless there is some gum related pathology present already.The infection in the wound has caused the swollen lymph nodes in the neck.

The non- healing and spreading nature of the ulcer needs to be investigated as it may be due to repeated trauma to the area or it is a chronic ulcer which needs a biopsy from its margin to rule out any malignancy.

Two important benign possibilities which can present with such symptoms are :

1) Gingivostomatitis which is an inflammation of the oral mucosa and gingival is common in young adults and has prodromal symptoms (fever, malaise, irritability, headache, vomiting, lymphadenopathy) 1-2 days prior to local lesions after which lesions appear inside the mouth forming small vesicles which rupture quickly, resulting in shallow, round, discrete ulcers with erythematous halo.
2) Aphthous ulcers in response to an infection
In gingivostomatitis, symptoms usually resolve with fluid intake, good oral hygiene and gentle debridement of the mouth. Use chlorhexidine mouth wash and avoid acid drinks, like fruit juices or fizzy drinks, or drink them through a straw so they don't irritate your mouth. Also avoid spicy food and sharp food and citrus fuits.

You can use topical ointments like numbing ointments, such as benzocaine (Oragel), anti-inflammatory (steroid) gels, benadryl allergy liquid mouthwash, oral preparations of steroids and vitamin supplement. Oral pain killers like Ibuprofen also help. But all these medicines are available under prescription and should be taken under a doctor’s guidance.

I hope my answer and recommendations are adequate and helpful. Waiting for your further follow up queries if any.
Wishing you good health.
Regards.

---