How should I act regarding the Zakat on money saved from previous years, knowing that I lent part of the money to someone in hardship, and that I have an amount allocated for feeding the poor as expiation? Is it permissible to sell a ring and a bracelet for the purpose of paying Zakat, or must the Zakat be paid from the saved money itself?

Zakat is not obligatory on cash unless two conditions are met: the attainment of the nisab (85 grams of gold or 595 grams of silver), and the nisab remaining for a full hawl (lunar year). If these conditions are not met, then you are not liable for Zakat for the past years. If you know that your cash reached the nisab and a hawl passed over it, then you must pay Zakat for every year that has passed. If you do not possess the money now, the Zakat remains an obligation upon you until you are able to pay it. Paying Zakat takes precedence over expiation, as Zakat is an obligation, whereas the expiation for an oath is something you brought upon yourself. If you do not find money for the expiation, then fast. It is not obligatory to pay Zakat from the same money; you may sell the bracelet and ring to pay the Zakat if you can do without them.