Answer: It does sound like overfertilization. Plants in containers, with their contained root systems, are quite susceptible to salt burn. The best way to ferilize containerized plants is to use a half-strength dilution of liquid fertilizer every 3=4 weeks. (Shultz's, Miracle-Gro, Peter's, etc.) This method of feeding will assure the roots have a steady supply of nutrients, but not so much the roots are burned. You can flush excess salts out of the potting soil by flooding it 2-3 times and allowing excess water to drain between each saturation.
Best wishes with your citrus tree!
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