Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain it seems that you are suffering from 
Hyperacidity leading to Acid reflux secondary to antibiotic intake and hyperacidity is one of the commonly seen side effect post antibiotic intake..
Secondly rashes on the different body parts can be due to developing 
allergic reaction to the antibiotic and it needs immediate stopping the intake of antibiotic..
For heartburn you can  take 
Proton Pump Inhibitors like Omeprazole or 
Pantoprazole..
Take antacids like 
Milk of magnesia half an hour before meals....
Avoid spicy food and drink plenty of water..
Always take walk after meals and take your dinner atleast 2 hours before sleep..
You should sleep with head slightly raised as compared to feet..
For rashes takes antihistamines like Benadryl..
Apply cool compresses over the rashes..
Application of steroid ointment can also help in reducing inflammation..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.