When something like a pandemic hits us, we problem solve and may postpone dealing with feelings. Like PTSD, the feelings can catch up with us months later. It is now months since the pandemic arrived. If we are used to being positive and dealing with problems, we may not have the ability to deal with negative feelings. We may have trouble describing how we feel but know that we are not at our best.
The challenge is to accept these feelings. We also need to name or label them. We need to admit that they exist as denying them will only cause them to get stronger and disrupt us further. Maybe sit with them for a short time. Let them in. Sad, tired, resentful, angry, depressed. Do this with someone you trust or do it alone. Accept that these feelings exist. Accept reality. It can be very tiring to deny what is. We are social animals and social distancing is unnatural for us even if we are introverts.