Citalopram is well known for causing insomnia, as are other SSRI's. I was having insomnia by about day 2 but with you not taken continued doses and the days elapsing I would think it would be very unlikely and more about the panic side.
Shock can have their effects for days on people like us when we are really struggling. I remember big like that myself.
I would suggest you ask about tapering up to reduce any impacts of meds you go on and because you are less likely to actually feel anything, your confidence will grow ready for the therapeutic dosages where side effects are more likely to feel tougher.