Struggling with fatigue

Hi, I am new to the forum but just looking for some reassurance I am not alone and hopefully some advice.

I was diagnosed with Stage 2 breast cancer in April this year. I had a lumpectomy and lipofiller to reconstruct my breast followed by a course of radiotherapy.

As my cancer is hormone PR & ER positive I am now taking Tamoxifen. I am 56 and was really struggling with Menopause prior to my diagnosis and was on HRT at the time to help with my symptoms. I was devastated I had to stop the HRT and absolutely terrified of taking a hormone blocker given how bad my symptoms were prior to this. 

I have been taking Tamoxifen for 3 months and have been suffering from fatigue which has become worse in the last few weeks. I initially took the Tamoxifen in the morning as advised but suffered from terrible flushes and night sweats along with disturbed sleep. About a month ago I changed to taking in the evening and this has definitely helped the hot flushes and night sweats but the fatigue is worse and I feel like my head is full of cotton wool and walk about like a zombie. 

I had initially hoped the fatigue was as a result of the radiotherapy and my body healing after surgery but I am now thinking it is the Tamoxifen which is causing it. I feel so awful I am not sure if I will be able to continue taking for the recommended 5 years. The other side effects are manageable but I am struggling to cope with feeling so tired.

Will this get better? I am hopeful and am trying to manage as best as I can. I exercise, eat healthy and gave up alcohol a few years ago so feel like I am doing everything I can.

Any advice would be appreciated as I feel totally alone in this.