Thanks for writing your query.
Pain in coccyx persists for few weeks to months after the injury.
Doing Sitz bath in addition to painkillers will be beneficial.
You can take painkiller like Ibuprofen one tablet twice a day after meals along with an antacid like Omeprazole
40 mg.(It will also help in relieving chest pain).
Also avoid sitting on hard surfaces. You should sit on soft/cushioned surfaces.
Diarrhoea and vomiting can be due to gastrointestinal infection
In addition to the above medicines, you can take Domperidone
10 mg once a day along with antibiotic like Ciprofloxacin
500 mg twice a day and an antiamoebic like Metronidazole
400 mg thrice a day.
You should also add a probiotic.
Eat light meals with less spice and oil and prepared under hygienic conditions.
If the problem persists, get yourself examined clinically.
I hope this is helpful to you.