Why do have I cramps but no period( I've done with...

are cramps a sign of pregnancy ?
it can be , but its neither deny or confirm it , you should do the tests to confirm the pregnancy 
- for pain , you can use paracetamol when needed 
What to do next ?
- if you have been sexual active recently , do home pregnancy test and if its positive , consult an OBGYN 
- if you havent been sexually active recently , do the following :
1. consult GYN doctor to do the needed routine medical test and determine the treatment pathways ( if needed ) 
2. in case of hormonal changes , doctor may prescribe medication to correct hormones imbalance such as duphaston , which you should take a pill every 12 hours for 5 days  
3. in case of thriod hormone abnormalties ( usually accompanied with other symtpoms ) , doctor will prescribe medication such as Levothyroxine
4. in case of other chronic disease such as ovarian cyst ( PCOS ) or other disease , doctor may need addvanced examnation to determine the causes and treatment pathway 
5. general advices :
- avoid stress  and have plenty of rest 
- healthy life style including health diet and regular exercise 
Needed medical examnation :
1. physical examnation 
2. Pregnancy test 
3. vaginal culture and urine test
4. productive system ultra sound 
5. hormone levels including productive system hormones and thyroid hormones