Recently i took lsd, and i'm still having mild effects 4 days later.. is this normal?

Not unusual: Some of the effects may last for many days and even weeks, and there is a small chance of "flashback" experiences, particularly in those whose experience was frightening and/or traumatic. It will likely resolve. One problem is that what is called lsd, which is relatively safe, may not be what it is billed as. It is sometimes pcp (phencyclidine or angel dust) which can cause severe mental reaction.