Sucralphate is a medicine with its own issues.
Your complete history is important.
Age 68 years, so shouldn't jump on to any conclusion. May be risky.
Next Steps
Get an ECG and Ultrasound whole abdomen done. Presume the Renal and
Liver function tests have been done.
Health Tips
May stop Sucralphate. May start Pantoprazole 40 mg once daily. Early morning, for 3 weeks.
Avoid too much tea/ coffee/ spicy/ greasy food