It's not your mic, it's the lack of signal processing.
Since we are talking about continuous speech and a performer who moves - you need to insert the following between your mic and the sound system:
1. Variable Low Cut filter
2. Variable High Shelf Filter
3. Resonant notch filters
There are a variety of ways or devices to accomplish this. You have to find what works for your budget and style. At minimal, an analog 15 or 31 band graphic EQ would give you a crude but effective way to accomplish all of 1 thru 3 above. Since you can find these used for about $50 it's your fastest and least costly solution if your mic is already going through a mixer.
The low cut should be used to roll off EVERYTHING below your voice range. Likewise the high shelf should dial down anything not required to give your speech definition. What remains is notches you create for a given room or setup that seems to be reactive.
For even more professional sounding results you'll need the following:
4. Gate
5. Compressor/Limiter
6. De-esser (optional)
A gate shuts of (attenuates) your mic whenever you're not actually speaking and terminates any chance of feedback.
Compression smooths your levels to keep you at a consistent sound level whether you speak calmly or get very animated.
A Limiter is hard compression at the top end to prevent you from exceeding a safe threshold before feedback or distortion.
De-essing removes excessive siblant noise from words with an "s, x, or "sh" sound. For example, say: "Excessive siblance" into your microphone and if you think it all sounds to much like a ssssnake - then you might need a de-esser.
There are dedicated mic processors that can do all of this in one piece of gear but, they are more expensive. An analog gated compressor/limiter will provide you with what you need again for about $50 used. A dedicated mic processor will save you space but run you $500, $800 or more. The advantage is that a mic processor will also include a pre-amp whereas all of the separate processors operate at line level and you'll need to put your mic through a mixer first.