2nd gear transmission problems

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I am having some problems with shifting into second gear. Yesterday while I was driving 2nd gear acting funny, it would either grind when going into gear or just take more effort than normal to put into gear. I first noticed it while doing a pull and when I went to shift from first to second the gears grinded, after that it became hard to shift into second with normal driving but sometimes it will go in just fine. I did one more high rpm shift from first to second and the same thing happened as the first time. Another symptom that has developed along side this is when I go into neutral and slow to a stop it will drop 150-250 rpms from idle and there is a clunking noise that come from the transmission for a few seconds then goes away. It doesn't happen every time but it has happened more than once and it is a lot more prevalent when using reverse. These problems just developed yesterday and I'm calling my shop tomorrow but if anyone has an idea on what might be wrong your help will be greatly appreciated.