What should one do if they had a bad dream a couple of weeks ago and still can’t forget about it?
Most dreams come from things that we have thought about or experienced in the recent past, (even up to 40 days). Even when a dream is from shomayim , one of the reasons is to help the person do teshuva. Another reason is that the pain and worry of the dream is itself heals the person.
The general rule with dreams is that we don’t know what the real interpretation of them is, and very often the real interpretation is the exact opposite. For example, when seeing someone die in a dream, it is a sign that they will live long!
If you are still nervous, there area number of things you should do; 1. say the teffilah for dreams during birkas koahanim, 2. daven, and 3. give tzedakah.
One of the reasons we have By the way, we never say that a dream is bad, only that it is scary, because we don’t want our saying that it is bad to be considered interpreting it as such. For example a person that sees a dead person in a house, is a siman for shalom bayis.
Rashi Berachos 55a, Pele Yoetz- Chalom, Divrei Chalomos pg 120