Question: Can tamoxifen,which is additionally taken during maintenance therapy with avastin after ovarian cancer treatment with chemo cause elevated ca 15-3 values??

I was diagnosed 2,5 years ago with ovarian cancer, had a debulking operation and then 6 cycles of chemo (taxol/platin); after that 12 months of maintenance therapy with Avastin only(every 3 weeks); PET-CT and all other imaging methods were then clear with no evidence of disease; shortly after, ca 15-3 value was rising (more significantly then ca 125 value!); my onc. said, who is making the follow up always with these 2 markers, that this is due to some recurrence in the reproperitonal area; in this case, not ca 125, but rather ca 15-3 is rising ??!! So they fould on the sigmoid colon a small knot, which was removed by surgery; after that anoyther 6 cycle chemo(Taxol/platin) was donr and since last 6 months a maintenance therpy with avastin(every 3 weeks) plus tamoxifen(orally every day, 20 mg) is ongoing; all imaging methods, like whole body and abdominal MRI; PET-CT, etc. scan showe no signs of any recurrence; in the last to blood tests, ca 15-3 started to trise slowly; from 24 to 28 to 33 and 3 weeks ago to 66; ca 125 againf was moving very slowly, from 5,8 to 5,5 to 8,2...meanwhile a urin analysis showed, lots of bacteria and some leucocytes; onc. said, the elevation of tumor markers van result from an gyno-urinary tract infection; so I was treated with cipro antibiotics, which I finished 1 week ago, a new urine test showed no bacteria, and very few leucocytes(within acceptable limits); tomorrow ı have another avastin treatment, but before, as they always due, they will make a blood analysis and determine the both tumor markers; I'm scared to death..I hope, that the elevated marker values 3 weeks ago are dure to the urinary infection..Wjhat is your opinion..please send it to me, if possible till this evening, as tomorrow morning I will be in the hospital..thanks
I am waiting for your opinion; would appreciate to have it asap, as I will be very early tomorrow morning in the hospital and will have no access to my e-mail.

I forgot to write to you, that my diagnosis 2,5 years ago was: ovarian cancer, 3c.

2 more questions:

-is it normal, that besides ca 125, the ca 15-3 value is determined every 3 weeks as a secondary marker??
- I started to take orally tamoxifene since 5-6 months, I have every time, after I have taken tamoxifene abdominal bloating; is this a isde effect of this drug and what can I do against it??