H thanks for your question
You had fall 2 weeks ago and injured your forehead on right side; this was followed by black purple eye, which got resolved.
Yes this normal part of healing and your forehead is still tender and you’re feeling a knot below skin.
The tenderness could be due to injury
to underlying bone and tissue.
The knot your mentioning below the skin could be small unresolved hematoma
(collection of blood under skin).which will also get resolved with time.
You can take painkiller for pain and apply hot fomentation to the tender portion of the forehead, this will help in resolving the hematoma.
Hope this answers your question.