Hello. Thank you for posting your query at DoctorSpring.com
I understand your concern.
Though there is not definitive way to say if you have a concussion without the CT, but most people who develop concussion following a trauma to their head will have symptoms such as headache, visual disturbances, and nausea/ vomiting, apart from the mood changes and sleep diturbances that can occur later. Nausea/vomiting is an very important sign, and i always instruct the patients to watch out for vomitting, following any head trauma. Since you have not developed any nausea/ vomiting tendency till now, it does not look like a concussion.
The blow was obviously very bad and the headache is what is causing you to feel grumpy. I will advise you to take Tab. Advil 400 mg three times daily in 6 hour intervals for 2-3 days depending on the pain severity.
However if your symptoms keep getting worse, and especially if you develop the nausea/vomiting tendency then CT becomes mandatory for diagnosis.
Hope this is helpful,