First and foremost, thank you for choosing justanswer.com. I am a licensed criminal defense attorney, Editor of PA DUI Defense, 3d., and member of the American Bar Association.
I am sorry for the traumatizing situation you were subjected to; a decent human being, shoplifting or not, should not be subjected to the above. You ask if you can sue Macy's and my simple answer is: Yes. I will provide your potential claims below:
(1) Intentional Infliction of Emotional Distress (IIED): A person may be sued civily under IIED if the person has subjected another individual to actions which a reasonably prudent individual knew, or should have known, would cause significant emotional distress. The person who "arrested" you in the above situation seems as though they did so in a manner in which any reasonably prudent individual would have known would cause you significant emotional distress. Hence, this is a potential claim.
(2) False Imprisonment: An individual may be sued civily under false imprisonment if they unlawfully subject an individual to physical restraint and that individual realizes they are subject to such confinement. In this case, you were locked in a room, while physically ill, and you were unable to free yourself. This seemingly was done in an unjust way as the person does not seem as though they have lawful ability to keep you detained. You realized you were locked in the room and, thus, this individual may be found liable for this tort.
(3) Negligence: A person may be sued for simple negligence if the individual owed a duty of care to you, breach that duty, and there is damages. In this instance, the individual who detained you owed you the duty of care to be sure you were not physically ill and he/she breached that duty when he/she did not seek medical attention on your behalf.
There may be even more claims, but these are the three main claims you may attempt to sue upon. You should talk to a Tort attorney immediately and discuss these aspects of your case.
I hope this helps. Please, click "Accept" if you found my answer helpful so I may be credited for my response. Do not hesitate to contact me via justanswer.com with any further questions or concerns. Thank you and good luck!!!