I am sorry to hear about your concern but will be happy to assist you.
It is better to avoid use of very old pads (more than 2 - 3 years and condition of packing) because it may contain some fungal growth. Sanitary pads are not supposed to be sterile like medical syringes etc, so if they have crossed the expiry date, they could be used.
Let's connect over a call so that we can discuss your concern in details and make a suitable treatment plan for you.