CheckboxList - Update - StoredProcedure

Question

Hi,
   I have table with 4 fields pkey,name,whosinfo_pkey,description.Here 'pkey' is autogenerated key. The sample values following here:

'75', 'Contact Dermatitis', '513', 'Contact Dermatitis'

'76', 'Anaphylaxis', '513', 'Anaphylaxis'

'77', 'Insect Venom', '513', 'Insect Venom'

'78', 'Atopic Dermatitis', '520', 'Atopic Dermatitis'

'79', 'Food Alergies', '520', 'Food Alergies'

'80', 'Insect Venom', '520', 'Insect Venom'

Here I want to update this table using whosinfo_pkey.I use following StoredProcedure for this

CREATE DEFINER=`root`@`%` PROCEDURE `SPUpdateMA`(in pkey varchar(45),

in DisName varchar(60)

)

BEGIN

UPDATE medicalhistory medhis

INNER JOIN whosinfo whos 

  ON whos.pkey=medhis.whosInfo_pkey

SET 

medhis.name=DisName,

/*medhis.whosInfo_pkey=pkey,*/

medhis.description=DisName

WHERE medhis.whosInfo_pkey=pkey;

END

In update button click I use following code:

try

                    {            

                       

                        if (whospkey == "")

                        {

                        }

                        else

                        {

                            //string patid = Request.QueryString["Ptid"];

                            for (int i = 0; i < CheckBoxList2.Items.Count; i++)

                            {

                                if (CheckBoxList2.Items[i].Selected == true)

                                {

                                    objReg.Name = CheckBoxList2.Items[i].Text;

                                    objReg.WhosInfo = whospkey;

                                    //  objReg.WhosInfo = Convert.ToString(ViewState["WhosInfo"]);                          

                                    objRegLogic.UpdatePMedHis(objReg);

                                }

                            }

                        }

                    }

                    catch (Exception ex)

                    {

                    }

In design page,I use checkboxlist as following:

 <asp:CheckBoxList ID="CheckBoxList2" runat="server" BorderStyle="Ridge" RepeatColumns="3"

                                    CssClass="CheckboxList" Width="100%" RepeatDirection="Horizontal" BorderColor="#3399FF">

                                </asp:CheckBoxList>

Here the problem is,when I update this it will update all data like following:

'75', 'Contact Dermatitis', '513', 'Contact Dermatitis'

'76', 'Anaphylaxis', '513', 'Anaphylaxis'

'77', 'Insect Venom', '513', 'Insect Venom'

'78', 'Anaphylaxis', '520', 'Anaphylaxis'

'79', 'Anaphylaxis', '520', 'Anaphylaxis'

'80', 'Anaphylaxis', '520', 'Anaphylaxis'

But actually I check 3 checkboxes.It takes last checkbox value only Hives,Food Allergies,Anaphylaxis.How I overcome this?How can I update values here correctly?Can anyone help me?