Someone anonymously paid over $5k worth of my rent for me. What should I do?

I (21F) currently rent an apartment right off my university campus in North Carolina, and my entire year lease is worth $8700, in monthly payments. I pay entirely for my rent and related expenses (my parents don’t contribute) but I guess they changed their mind and wanted to pay my utilities/rent for me as a surprise or gift? So they called my leasing office attempting to, and were told by the manager that my rent has actually been paid all the way up until June….the lease ends in July.? The manager was not able to tell my stepmother how it was paid, and the manager didnt think I knew it was paid either?? All they said was that the payment was sent with my name and my apartment number on it, but the donor did not want me or my stepmother to know who they were? What my mom said after telling me was weird too, she said “Maybe try not to worry about where it came from and be thankful for the generosity of others.” But I just can’t accept this? What if it’s a mistake or filing error? Are my parents lying to me? Who would send over $5k in a money order or check (my complex does not accept card payments or cash) in the mail? Or hand deliver it in person? Why didn’t the donor want me to know who they were?

I have so many questions and thoughts. This whole situation is weird and I am very anxious and paranoid, I feel like I’m being watched in my house now or something , not many people know where I live or my exact address :( What should I do?