What to do with a strange, sudden absence of pleasure?
Context: Hello, I practice mindfulness of breath ~45min every morning, along with daily walking meditation. My practice has recently become less effortful, and I can reach a deep focus. Whenever I meditate, I feel energy and pleasant sensations rising together, usually within first five breaths -- I've only recently been able to tell the two apart, seeing one arise separately from the other. These same sensations appear outside of meditation, when my concentration/awareness are strong.
Situation: Last Sunday, I had a rare day free of obligations, so after seated meditation I went for a long walk. My concentration was unusually strong, to the point that when I stopped at red lights and exclusively attended my breath, I immediately fell into a deep concentrated state. The practice was so effortless and rewarding that I continued it, and after walking 2hrs, I took a train, and my mind was so calm that I immediately resumed seated meditation for the duration of my trip, after which I resumed walking meditation, etc. I spent over 5hrs in near-continuous meditation, a first by a long shot - and I felt a tremendous amount of energy (almost like I was overcaffeinated, but pleasantly), far fewer discursive thoughts, great joy.
The next day (yesterday), I woke up and did my seated meditation. While I reached a deep state, I felt little energy arising and almost no pleasure. It was strange. I did some walking meditation later in the day, and felt more energy and limited joy, but just a hint, despite strong mindfulness. This morning, I woke up and feeling calm and ready, I did seated meditation. I felt some pleasure, perhaps a little more than yesterday, but it was very limited, although the energy was stronger and I felt it start to build. My concentration was strong, and I was able to reach a state where my breath fell off, and my heart beat wasn't accessible for some reason, so I searched for an object for my attention. Usually this is blankets of pleasant feelings settling in my body, but today only the tiniest wisps of pleasant came and went, and I maintained mindfulness without a reliable object until my breath slowly returned. I did mindful walking afterwards, and felt strong energy building, but almost no pleasure.
Question: Has anyone experienced this near absence of pleasure before? What do you do with this? I don't believe I should judge the experience, yet I'll be transparent and say I'm not enjoying it. I felt unsettled after seated meditation, as if it were borrowing a body. (I don't want to overstate this as a non-dual insight, just an unpleasant feeling.) I'm considering taking a couple days off, or just practicing walking meditation.
I'm in the process of finding a teacher, have reached and and am awaiting responses. Thanks!