Hi.. Thanks for the query.. Mouth ulcers can be a side effect of antibiotic while at times they are also seen due to infection caused due to cold and flu and yes, excess of cough drops can also irritate the tongue and cause ulceration .. So do not worry about it as it will be resolved soon.. For now you can start gargling with Magic Mouthwash or other brands that contains numbing agents like Lidocaine that helps in reducing pain over the ulcers, along with it you can also start doing warm saline gargles to soothe the tongue, take a Vitamin B complex supplement daily, avoid spicy and hard foods and drink plenty of cool water.. In case if the ulcers does not resolve in another one week then you can check with an Oral Physician who can examine and take an oral swab culture for viral infection causing cold sores and treat you accordingly.. Hope this helps.. Regards..